msync(2)                                                              msync(2)



NAME
     msync - synchronize memory with physical storage

SYNOPSIS
     #include <sys/types.h>
     #include <sys/mman.h>

     int msync(void *addr, sizet len, int flags);


DESCRIPTION

     The function msync writes all modified copies of pages over the range

     [addr, addr + len) to their backing storage locations.  msync optionally

     invalidates any copies so that further references to the pages will be

     obtained by the system from their backing storage locations.  The backing

     storage for a modified MAPSHARED mapping is the file the page is mapped

     to; the backing storage for a modified MAPPRIVATE mapping is its swap

     area.


     flags is a bit pattern built from the following values:


          MSASYNC                 perform asynchronous writes

          MSSYNC                  perform synchronous writes

          MSINVALIDATE            invalidate mappings


     If MSASYNC is set, msync returns immediately once all write operations

     are scheduled; if MSSYNC is set, msync does not return until all write

     operations are completed.


     MSINVALIDATE invalidates all cached copies of data in memory, so that

     further references to the pages will be obtained by the system from their

     backing storage locations.


     msync will fail if:


     [EINVAL]       If addr is not a multiple of the page size as returned by

                    sysconf(3C).


     [EIO]          An I/O error occurred while reading from or writing to the

                    file system.


     [ENOMEM]       Addresses in the range (addr, addr + len) are outside the

                    valid range for the address space of a process or pages

                    not mapped are specified.


     [EBUSY]        MSINVALIDATE was specified and one or more of the pages

                    was locked in memory.


SEE ALSO

     mmap(2), mpin(2), sysconf(3C).







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msync(2)                                                              msync(2)



DIAGNOSTICS
     Upon successful completion, the function msync returns 0; otherwise, it
     returns -1 and sets errno to indicate the error.

NOTES
     msync should be used by programs that require a memory object to be in a
     known state, for example, in building transaction facilities.
















































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